Causality
by The Lady Wolfshead
Summary: *Book 5 Spoilers* The most fundamental rule of time travel is not to change anything. To tinker with the fate of one individual will change the world. But that doesn't matter to Harry...


BOOK 5 SPOILERS! Just something that needed to be done. Disclaimer: I own nothing connected to Harry Potter. All I own is the plot of the story.  
  
*  
  
Harry lay on his bed at Number Four, Privet Drive, fingering his mirror and thinking about Sirius. He closed his eyes and watched his memories, replaying his emotions. The news of Sirius' escape from Azkaban. Helping Sirius escape from Buckbeak. Meeting Sirius as Snuffles in Hogsmeade, with food he had taken from the Hogwarts kitchens. The brief moment of joy he had felt when Sirius had asked him to come and live with him.  
  
Harry drew a deep, shuddering breath and tried in vain to stop the tears trickling down his cheeks. Now there was no hope of living with his godfather, no more secret messages from Snuffles, no more secret meetings by firelight. Sirius was gone. He felt desolate, empty, abandoned. He felt lost.  
  
His eyes fixed on his Firebolt, 'thirteen birthdays worth of presents' from his godfather. He got up from his bed, took his broomstick, and sat back down with it across his knees, stroking the handle distantly, his eyes gazing at nothing.  
  
It's my fault, he thought miserably. It's all my fault. If only I hadn't been stupid enough to go believing Voldemort's tricks, if only I had stopped to think, if only . . .  
  
If only . . .  
  
Such words were useless, he knew. There was no point in dwelling on 'If only's. The only power those words had was to drive people mad. It was useless just wishing someone back from the dead anyway. It never worked. And hadn't Dumbledore himself said no spell on Earth could bring back the dead? There was nothing he could do. He would just have to accept it.  
  
No! He would not accept it! He would not accept that there was nothing he could do to bring Sirius back. He would see him again, he *would*! There must be *something*!  
  
Harry sat bolt upright suddenly, his heart hammering in his chest, a crazy idea forming in his mind. He *could* do something! What if . . . what if he could somehow turn back time and rescue Sirius? Somehow stop him falling back through the veil? Then he would still be here, he could go and see him!  
  
Harry started rummaging through his school trunk, looking for books with spells that might have some sort of link to time-travel. Come on, he thought desperately, opening books at random and rifling through pages, there must be something, anything!  
  
His eyes fell on an old, tattered book right at the bottom of his trunk. Strange, he thought, I don't remember that. maybe Hermione lent it to me for the DA and I forgot to give it back? He opened the book and started scanning the pages.  
  
His heart leapt as he found the spell he was looking for. It was a potion, Tempus Vehere, not too complex, brewable within a few hours. He had most of the ingredients to hand, and the rest . . . they were easy to get or grew nearby, crushed daffodils trumpets, a lump of coal, a pinch of sand . . . the other ingredients grew near the park. One sip of the potion would send the drinker back in time for precisely half an hour. They just had to focus on what time they wanted to get back to. There was a warning about one's conduct when travelling through time, but Harry skipped that bit and glanced at his watch. It was nearly eleven in the evening. The Dursleys would be asleep. He would go now, covered by the Invisibility Cloak, to the common surrounding the park. By morning he would have his godfather back!  
  
Harry hesitated momentarily, remembering the Decree for the Reasonable Restriction of Underage Sorcery - he was clearly breaking the rules here and would almost certainly be expelled from Hogwarts because of it - but, he reasoned, if I do save Sirius, then I won't have needed to brew the potion so I wouldn't have done it, so I wouldn't be expelled. He grabbed his things, flung the Invisibility Cloak over his shoulders, and crept out of the house.  
  
The stars were just beginning to fade when Harry, thoroughly exhausted, finished brewing the potion. It had been easy! Especially as there was no Snape breathing down his neck, making him forgetful. Besides, it was hardly as complex as some of the potions he had brewed last year . . .  
  
If Harry had been thinking clearly instead of driven by a burning desire to change the past, he might have wondered at that fact. In fact, it had almost been too easy . . .  
  
But he wasn't, and, with a triumphant smile and picturing clearly in his head the battle in the Department of Mysteries, he raised a phial full of the potion and took a sip.  
  
He felt the world around him spin, all the colours of the pre-dawn landscape blurring and melting into one, until he fell to the floor with a violent thud that knocked his glasses off his face.  
  
He reached for them and put them back on, glancing wildly around. This wasn't the room of the battle! He thought desperately, then realised he could hear screams and yells nearby. He followed the sound, his heart thudding, and almost walked straight into the battle. Remembering what Hermione had said about not being seen that time they used the Time Turner, he hid himself behind a statue and watched the battle, his eyes fixed on Sirius and Bellatrix.  
  
He saw Dumbledore arrive, saw the Death Eaters stop duelling, saw Bellatrix raise her wand to fire the spell that would kill his godfather . . .  
  
NOW! He raised his wand and shouted "EXPELLIARMUS!" Bellatrix was knocked off her feet, and her wand flew through the air, landing with a clatter several feet away. Sirius looked around for his mystery saviour, but in vain - the potion was wearing off, and Harry was on his way back to his own time. 


End file.
